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Running power to radio

Discussion in 'Mobile Radio Systems' started by WX4WSD, Sep 26, 2020.

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  1. N7WR

    N7WR Premium Subscriber QRZ Page

    I have done hundreds of mobile radio installations (public safety and ham radio). I have yet to find any vehicle (and that includes former military Humvees and MRAPS) where there was not some place to get through the firewall. Existing feed throughs with grommets or, as a last resort, drill a separate hole. It does not need to be a large hole since you simply need to route the positive wire through it. The negative (ground) can be affixed to the body inside the passenger compartment. If you drill a new hole use a grommet to protect the wire and silicone any space between the wire and grommet to prevent moisture intrusion.
    SLOWMOVER, W9WQA and K7JEM like this.
  2. NG1H

    NG1H XML Subscriber QRZ Page

    Just guessing but for a while there was a troll harassing him every time he posted anything.
  3. KB0MNM

    KB0MNM Ham Member QRZ Page

    The Ford Ranger is a small pickup truck, and I once owned an older version. You will probably need to carefully dis-assemble the passenger side trim at the 'doorsill' edge where feet typically cross when boarding, plus the plastic "V" shaped interior plastic closer to the engine. There is likely at least one screw holding that part. Once that has been accomplished, you should be able to get underneath the place where the passenger would keep their feet. Just forward of there, on the area that slants toward the engine- there is typically a 'drain plug' which can be removed carefully- do not lose it. The only other things to remember are this: 1. Water from below the truck is constantly being splashed, and will cause your carpet to mold unless the seal is made watertight. 2. Tiny rocks & sand are also kicked up, so sleeving ( such as convoluted plastic loom ) is a great idea to keep the wire from being abraded ( worn to the conductor ). 3. There are plenty of hot and moving parts inside that engine compartment. Use high-quality black ( UV resistant ) Tie-wraps(TM) or other fasteners- not just tape- to keep the wire that you fuse on the battery side of the firewall where it needs to be- not getting too hot or being cut by movement. Personally, I like to double-insulate that positive lead where it enters the cab- because that is where most short circuits occur- due to wire movement. Small sleeving as in heat-shrink tubing or convoluted loom works fine. For a more sophisticated install, pull a small wire 18-20 AWG in a color other than red or black- to use for an ignition sense relay. Later, you can conserve battery power by turning the power to the radio off with the key and a relay powered by the ignition fuse ( tapped ) in the fuse box.
    N1IPU likes this.
  4. K9RKA

    K9RKA Ham Member QRZ Page

    I would be cautious about drilling in your new ford. I know the full size trucks have gone to aluminum bodies and would expect the ranger has as well. Unless there's a trick to it, I've seen a few pictures of those that have tried drilling an NMO hole in the roof, only to destroy the roof panel itself.
  5. N1IPU

    N1IPU Premium Subscriber QRZ Page

    Go with a greenlee punch. If you don't have experience drilling with a stepbit in thin sheet your in for a surprise. I stepbit to 3/8 then install the greenlee and gently wind it.
  6. KB0MNM

    KB0MNM Ham Member QRZ Page

    Here is the area within the website that you might look at: Installations ( this should provoke ) : Contents: Ford F-series, and other aluminum-bodies vehicle; Basics; Airbags Are Dangerous!; Doing it Right; Mounting Options; Odds & Ends; So between pulling in an 8 AWG red wire, and at least one more ( 18 or so AWG ) if you desire ignition sensing, and what K0BG has on his website- the power and mounting should be covered. Ref. Post #19 Personally, I was once asked to use the vents at the lower back corners of a pickup cab- yet later the direction was given to go through the firewall area instead. I think that someone decided that the vents would be considered an 'air plenum', which in building trades calls for a 'plenum rated' wire. The difference is just in what happens if the wire gets very, very hot. And regarding the website, ( Ref. RFI- see that last paragraph first ) - I have no problem using a R.S. P/N 270-055 "20AMP HEAVY DUTY NOISE FILTER" when installing a radio. Some folks would say " that is masking a problem, rather than solving the root cause "- to which I say: in some cases, it is needed because there is no cure for other noisey equipment. So the radio that you install may or may not require this small module, less than 3" x 4" x 2" and a terminal block. I like the larger 'european style' barrel / setscrew types- yet many will work.
    Last edited: Oct 16, 2020
  7. K6CPO

    K6CPO Ham Member QRZ Page

    I have a 1998 Dodge Dakota with 318 V8 engine. They had to use a shoehorn to get that engine into that small a truck, so there is virtually no access to the firewall from the engine side. I ran the power wires for my radio around the driver's side "A" pillar and then down to under the step plate on the door opening. From there it runs under the driver's seat where it connects to the radio. The power wiring was installed in 2011 and has powered four different radios to date. There's enough space between the pillar and the door that there is no pressure on the wire and it's in a position where it gets inspected every time I get into the truck. To date the wiring looks like it was installed yesterday.
    SLOWMOVER likes this.
  8. WN1MB

    WN1MB XML Subscriber QRZ Page

    Actually the vehicle is built around the engine, drive train, and chassis. I learned this the hard way back in the early 70s when trying to remove the heater shroud on a GMC pick up truck.

    That 318 is a sweet block.

    One doesn't see engines being lowered into engine compartments much these days.
  9. N1IPU

    N1IPU Premium Subscriber QRZ Page

    I tend to go one wire size greater than required and use marine rated cable in my mobile installs and everything gets wrapped.
  10. KC9OO

    KC9OO Ham Member QRZ Page

    There is a grommet on the passenger side that has enough rubber on it that you can poke a hole through it and run your wires. This is on my 2019 Ranger. I run the power leads from the battery, across the firewall to this grommet. The wires come in, run under the center console and then under the passenger seat where the body of my IC-5100 is. Been working for a year.


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